A conventional complex wrench is shown as U.S. Pat. No. 1,793,714, which includes one strip-shaped shank. The shank has a smooth metal surface. The middle section of the shank has one twisted section. Each of the two ends of the twisted section horizontally extends to connect an open-shaped driving head. The patented complex wrench has a twisted section to enhance the holding convenience, but its shank has a smooth metal surface which is easy to slip off user's hand. Besides, its shank doesn't have an embossed mark to indicate the size of the main body. When the user wants to select a tool of required size from many main bodies, it is very easy for the user to take a tool of incorrect size because the main body doesn't have an embossed mark.